1. Field of the Invention
This invention relates to systems for protecting health and safety of medical personnel during laser surgery. More particularly, the present invention is directed to a self-contained air enhancement system for evacuating and processing the laser plume created by the laser surgery.
2. Background Art
The use of lasers in surgery has rapidly expanded in recent years. Initially, lasers were found to be particularly useful in very delicate precision surgery. As a result, laser eye surgery and other types of microsurgery became well accepted during the 1970's. Indeed, many laser surgical devices incorporated a microscope into a laser source so that the area on which surgery was performed could be adequately and accurately viewed.
Since the introduction of lasers into surgical procedures, lasers have found utility in areas outside of microsurgery. For example, lasers have currently found wide acceptance in gynecological surgery.
With the rapid expansion in the use of lasers as surgical instruments, new problems have been encountered which have not been confronted in conventional surgery. One such problem is that of the smoke or laser plume produced during laser surgery. While some smoke may be produced by conventional electric scalpels and similar devices, the intensity and volume of the smoke and pollutants produced in laser surgery presents a problem of much larger magnitude.
The high intensity of lasers used in laser surgery causes oxidation of tissue and fluid contacted by the laser. This typically results in a dense laser plume emitted from the surgical site. The laser plume contains a variety of hydrocarbon compounds, carbon monoxide, moisture, and unpleasant odors. It is also now conjectured that the laser plume may contain quantities of biologically viable material, which could range in content from relatively benign organisms to cancerous and deadly viral materials.
In one study which sought to determine the scope and intensity of the smoke produced during surgery, tissue was contacted by a laser under controlled conditions. It was found that the smoke and particulate matter produced amounted to almost 7.9 milligrams per cubic meter. This smoke density is approximately 52 times greater than the recommended density set by the governmental regulatory agencies.
In addition, the laser plume is known to contain particles of varying sizes. For example, one investigation found particles varying in size from under 0.4 microns to over 9.0 microns. Nevertheless, a large portion of the particles found in that study were under 1.1 microns in size which are capable of being easily deposited in the alveoli of the lungs. Not only are particles of this size irritating to the respiratory system, but they may also be capable of causing serious respiratory disease. Repeated exposure to such particles can build deposits within the lungs.
Several investigators have pointed out that repeated exposure to laser plumes may, for example result in pneumonitis. In addition, it has been found that the laser plume may be mutagenic, and thus possibly carcinogenic. The presence of biological viable materials poses the risk of the spread of contagions. While much of the data in this area is still not definitive, it is clear that direct contact with laser plumes presents significant health risks, particularly to exposed medical personnel and patients.
Laser plumes present additional difficulties. For example, it has been found that the laser plumes condense on the optical components of the laser itself, thereby impairing visibility or causing pitting damage to lenses. Similarly, the laser plume may enter and clog mechanical devices and filters located in the operating room.
In order to combat the problems of damage to the laser itself, many conventional laser systems are equipped with air circulation systems. These systems drive a stream of air over the sensitive laser equipment and the area being contacted by the laser beam. While the laser plume is thus driven away from the laser equipment, it is forced into the ambient air, making it more difficult to control laser plume emissions.
Also, the superheated steam component of the laser plume may cause serious burns in the event of contact with the flesh. Of course, the primary danger in this regard is to the patient. The steam is produced by vaporizing irrigation or body fluids, and there is a danger that those vaporized fluids may contact the surrounding tissue.
When the steam does leave the localized surgical site, there is a danger that the heat may cause discomfort or otherwise provide an undesirable distraction to the surgeon or other operating room personnel. Thus, it is important that the steam produced in laser surgery be controlled and removed from the surgical site before it injures the tissues surrounding the surgical site or becomes a problem to operating room personnel.
Good practice thus dictates that the laser plume be controlled and removed from the surgical site, and various devices have been developed for this purpose. Most involve the use of some form of suction.
The initial attempts to remove the laser plume simply used the vacuum system built in to the operating room. This solution, however, proved to be unsatisfactory because such vacuum systems are not equipped to handle the dense hydrocarbon saturated smoke and associated moisture contained within the laser plume. Untreated laser plumes have been found to be capable of clogging and completely disabling an entire built-in hospital vacuum system.
Laser surgery often requires intense concentration on the part of the surgeon and other assisting medical personnel. It is desirable to keep machinery and distractive noise in the operating room to a minimum. A significant disadvantage of the use of a portable vacuum system is the undesirable noise it introduces into the operating room. Portable systems have limited filter capacity. There filters become easily clogged with the particulate debris and other matter, rendering them ineffective.
Clogged filters cause resistance to air flow through the system, causing inefficient laser plume removal. Filters of conventional systems must thus be replaced quite often to ensure that suction levels are adequate for removing the laser plume from the surgical site. This results in increased maintenance costs, as well as in disruptions to the surgical procedure.
Studies have been performed concerning various methods for removing laser plumes. It has been found that if a suction device having appropriate air flow rates can be placed within approximately 1 centimeter of the source of the laser plume, then over 98% of the smoke and debris will be removed before entering the ambient air. If the suction source with the same air flow is placed 2 centimeters from the source, however, only slightly over 50% of the smoke in the plume is removed. Thus, in the setting of the surgical theatre, it is important that laser plume removal systems be flexible and maneuverable, not bulky and hard to handle.